DULUTH – Minnesota Attorney General Keith Ellison has filed a brief supporting a lawsuit in Michigan seeking the shutdown of the Enbridge Line 5 pipeline, which starts in Superior, Wis., and runs underwater across the Straits of Mackinac that connects Lakes Michigan and Huron.

In a friend-of-the-court brief filed this week with Wisconsin Attorney General Joshua Kaul and California Attorney General Xavier Becerra, they argue that state law, not federal, controls the routing of pipelines.

Ellison said in a statement that he joined the brief to support Michigan “in protecting its right to control its underwater land against the federal government’s attempt to pre-empt it. The people of Michigan, who share the Great Lakes with us, have as much of a right to control their underwater land as the people of Minnesota do. By supporting Michigan, I’m protecting Minnesotans.”

The filing “expresses no opinion as to whether plaintiff’s claim should ultimately succeed.”

Michigan Attorney General Dana Nessel filed the suit in June in Ingham County Circuit Court, saying the 66-year-old Line 5 pipeline “violates the public trust doctrine, is a common law public nuisance, and violates the Michigan Environmental Protection Act because it is likely to cause pollution impairment and destruction of water and other natural resources.”

Enbridge has asked the court to dismiss the case and said “Line 5 has been safely operating across the Straits for more than 65 years” spokesperson Juli Kellner said in a statement. “There is no change in the operating condition of the pipeline or change in law to support the Attorney General’s position.”

Enbridge said a shutdown of Line 5, which carries up to 540,000 barrels of oil and natural gas liquids per day, would have “immediate and severe consequences” for refineries, jobs and fuel prices in Michigan, Ohio and Ontario. The line begins at the Enbridge terminal in Superior and ends in Sarnia, Ontario, across the Michigan border.

The multistate brief filed Tuesday is unusual for a case in state court, though it does address the collision of state and federal powers concerning coastline and public water management.